Under high stress we reduce some perceptual and cognitive capacities of our brain.

 

Under high stress, we lose some of our perceptual and cognitive abilities

Thousands of years ago, when a predator approached, the human body did not schedule a meeting to consider its options.

It activated the fight-or-flight response.

The heart began to beat faster. Blood pressure rose. Breathing accelerated. Adrenaline, noradrenaline, and cortisol were released. More glucose became available, blood flow was redirected to the muscles, and the body prepared for immediate physical action. Strength, speed, alertness, and resistance to pain temporarily increased.

This response made perfect sense. When facing a large predator, our ancestors did not need to develop a long-term strategy, challenge their initial assumptions, or generate three innovative solutions. They needed to fight, flee, or become lunch.

The body therefore prioritised the abilities most useful for immediate survival. The cost was a reduction in some of the perceptual and cognitive capacities needed for more complex situations.

Psychologist Matthew J. Sharps explains that under intense stress, attention becomes narrower and increasingly focused on what appears to be the main threat. Peripheral information may be ignored. Working memory becomes less efficient, so it is harder to hold several pieces of information in mind and compare them. Cognitive flexibility declines, making it more difficult to change perspective or abandon an ineffective approach.

Complex reasoning, impulse control, planning, evaluation of alternatives, and conceptual or creative thinking may also deteriorate. Instead of adapting our behaviour to new circumstances, we become more likely to rely on familiar habits and automatic responses.

This shift is sometimes described as the brain entering a “reptilian mode.” Taken literally, that explanation is not accurate. The popular model dividing the brain into a reptilian brain, an emotional mammalian brain, and a rational human brain is now considered outdated. The brain does not contain three separate systems that take turns controlling us.

The metaphor does, however, point towards a real change. As stress intensifies, the prefrontal cortex loses some of its ability to exercise flexible, top-down control. Faster systems involved in detecting threats, initiating defensive reactions, and repeating learned habits gain greater influence over behaviour. We become more reactive, defensive, and rigid—and less capable of reflection, inhibition, and considering alternatives. The brain does not literally become reptilian. It does begin to favour survival responses that are evolutionarily older, faster, and less intellectually sophisticated.

This is not necessarily a flaw. In an immediate physical emergency, careful reflection can be dangerously slow. A firefighter, police officer, soldier, or paramedic may act effectively because the correct response has been practised until it becomes automatic.

The problem begins when the automatic response does not fit the situation.

Modern stress rarely involves a predator emerging from the forest. It is more likely to involve an urgent email, an unrealistic deadline, several conflicting tasks, a difficult conversation, constant interruptions, or a manager who has discovered that everything can be labelled “high priority.”

The body, however, does not always appreciate the distinction. It can respond to social and professional pressure using a system designed for physical survival.

The result is a curious mismatch. The modern problem may require perspective, restraint, careful analysis, creativity, and the ability to combine several incomplete pieces of information. Stress pushes the mind in the opposite direction: towards tunnel vision, rigid thinking, impulsive judgement, and familiar reactions.

Despite this, employers frequently include “the ability to work under pressure” in job advertisements. Read literally, this may suggest that they are not looking for someone who thinks well under pressure at all. Perhaps they are looking for someone who stops thinking ...

An impressive requirement.

A company wants original ideas, sound decisions, attention to detail, strategic thinking, adaptability, and excellent communication. It then creates an environment that narrows attention, weakens working memory, reduces cognitive flexibility, and encourages automatic behaviour. Finally, it asks why nobody is thinking outside the box—while applying enough pressure to make the box the only thing anyone can see.

What exactly do we expect from the human mind?

Do we want it to react quickly or think deeply? Repeat proven behaviours or develop new ideas? Defend itself from danger or remain open to complexity? And if we expect judgement, creativity, learning, and intellectual flexibility, what conditions make those abilities possible?

We often discuss human performance as if the brain were a machine whose output could be increased simply by turning up the pressure.

Well, no. That is not how it works.

Sources

• Matthew J. Sharps, How We Process Under Pressure: Stress and Automatic Behavior, Psychology Today
• Amy F. T. Arnsten, Stress signalling pathways that impair prefrontal cortex structure and function, Nature Reviews Neuroscience
• Steffen et al., The Brain Is Adaptive Not Triune: How the Brain Responds to Threat, Challenge, and Change, Frontiers in Psychiatry